Re: [PATCH V13 7/8] gdbstub: Add helper function to unregister GDB register space

[Igor Mammedov <imammedo@redhat.com>]

On Fri, 7 Jun 2024 12:56:48 +0100
Salil Mehta <salil.mehta@huawei.com> wrote:

> Add common function to help unregister the GDB register space. This shall be
> done in context to the CPU unrealization.
> 
> Note: These are common functions exported to arch specific code. For example,
> for ARM this code is being referred in associated arch specific patch-set:
> 
> Link: https://lore.kernel.org/qemu-devel/20230926103654.34424-1-salil.mehta@huawei.com/
> 
> Signed-off-by: Salil Mehta <salil.mehta@huawei.com>
> Tested-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com>
> Reviewed-by: Gavin Shan <gshan@redhat.com>
> Tested-by: Xianglai Li <lixianglai@loongson.cn>
> Tested-by: Miguel Luis <miguel.luis@oracle.com>
> Reviewed-by: Shaoqin Huang <shahuang@redhat.com>
> Reviewed-by: Vishnu Pajjuri <vishnu@os.amperecomputing.com>
> Tested-by: Zhao Liu <zhao1.liu@intel.com>
> ---
>  gdbstub/gdbstub.c      | 13 +++++++++++++
>  hw/core/cpu-common.c   |  1 -
>  include/exec/gdbstub.h |  6 ++++++
>  3 files changed, 19 insertions(+), 1 deletion(-)
> 
> diff --git a/gdbstub/gdbstub.c b/gdbstub/gdbstub.c
> index b3574997ea..1949b09240 100644
> --- a/gdbstub/gdbstub.c
> +++ b/gdbstub/gdbstub.c
> @@ -617,6 +617,19 @@ void gdb_register_coprocessor(CPUState *cpu,
>      }
>  }
>  
> +void gdb_unregister_coprocessor_all(CPUState *cpu)
> +{
> +    /*
> +     * Safe to nuke everything. GDBRegisterState::xml is static const char so
> +     * it won't be freed
> +     */
> +    g_array_free(cpu->gdb_regs, true);
> +
> +    cpu->gdb_regs = NULL;
> +    cpu->gdb_num_regs = 0;
> +    cpu->gdb_num_g_regs = 0;
> +}
> +
>  static void gdb_process_breakpoint_remove_all(GDBProcess *p)
>  {
>      CPUState *cpu = gdb_get_first_cpu_in_process(p);
> diff --git a/hw/core/cpu-common.c b/hw/core/cpu-common.c
> index 0f0a247f56..e5140b4bc1 100644
> --- a/hw/core/cpu-common.c
> +++ b/hw/core/cpu-common.c
> @@ -274,7 +274,6 @@ static void cpu_common_finalize(Object *obj)
>  {
>      CPUState *cpu = CPU(obj);
>  
> -    g_array_free(cpu->gdb_regs, TRUE);

so free() is gone but new  gdb_unregister_coprocessor_all() ain't called,
are we staring to leak some memory here?

>      qemu_lockcnt_destroy(&cpu->in_ioctl_lock);
>      qemu_mutex_destroy(&cpu->work_mutex);
>  }
> diff --git a/include/exec/gdbstub.h b/include/exec/gdbstub.h
> index eb14b91139..249d4d4bc8 100644
> --- a/include/exec/gdbstub.h
> +++ b/include/exec/gdbstub.h
> @@ -49,6 +49,12 @@ void gdb_register_coprocessor(CPUState *cpu,
>                                gdb_get_reg_cb get_reg, gdb_set_reg_cb set_reg,
>                                const GDBFeature *feature, int g_pos);
>  
> +/**
> + * gdb_unregister_coprocessor_all() - unregisters supplemental set of registers
> + * @cpu - the CPU associated with registers
> + */
> +void gdb_unregister_coprocessor_all(CPUState *cpu);
> +
>  /**
>   * gdbserver_start: start the gdb server
>   * @port_or_device: connection spec for gdb